Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		3 Months Ended			3 Months Ended
	Dec. 31, 2013 Respirator Liabilities [Member] claimants	Sep. 30, 2013 Respirator Liabilities [Member] claimants	Dec. 31, 2012 Maximum [Member] Respirator Liabilities [Member]	Dec. 31, 2013 Environmental Matters [Member]	Sep. 30, 2013 Environmental Matters [Member]	Dec. 31, 2013 Environmental Matters [Member] Maximum [Member]	Dec. 31, 2012 Environmental Matters [Member] Maximum [Member]
Loss Contingencies [Line Items]
Reserve for environmental matters on discount				$ 5	$ 5
Reserve for environmental matters on undiscounted basis				5	5
Cash payments for environmental reserves						1	1
Number of claimants	42,000	42,000
Respirator reserve on discounted basis	10	11
Respirator reserve on undiscounted basis	14	15
Cash payments for respirator reserves	$ 2		$ 1